Under the auspices of this grant we are proposing to continue our analysis of the hypothetical chain of events occurring in synovial fluids of patients with rheumatoid arthritis. Particular attention will be directed towards a better understanding of the role of rheumatoid factor by 1) comparing the complex fixing ability of S19 and S7 rheumatoid factor, 2) investigating potential differences in complement fixing ability of rheumatoid factors derived from rheumatoid serum as compared to those from synovial fluid, 3) studying the importance of the antigen in these complement fixing reactions, and 4) observing the manner by which rheumatoid factor might cause elaboration of fragments which have chemotactic activity from the complement sequence.